/Engine/Plugins/Importers/USDImporter/Source/GeometryCacheUSD/Public/GeometryCacheUSDStream.h
Derived class must provide a way to get the mesh data for the given FrameIndex, called from worker threads
virtual void GetMeshData ( int32 FrameIndex, int32 ReadConcurrencyIndex, [FGeometryCacheMeshData](API\Plugins\GeometryCache\FGeometryCacheMeshData) & OutMeshData )